<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8" />
  <meta http-equiv="X-UA-Compatible" content="IE=edge" />
  <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  <title>栈的封装</title>
</head>

<body>
  <script>
    // 封装栈类
    function Stack() {
      // 栈中的属性
      this.items = []

      // 栈的相关操作
      // 1.将元素压入栈
      Stack.prototype.push = function (element) {
        this.items.push(element)
      }
      // 2.从栈中取出元素
      Stack.prototype.pop = function () {
        return this.items.pop()
      }
      // 3.查看一下栈顶元素
      Stack.prototype.peek = function () {
        return this.items[this.items.length - 1]
      }
      // 4.判断栈是否为空
      Stack.prototype.isEmpty = function () {
        return this.items.length == 0
      }
      // 5.获取栈中元素个数
      Stack.prototype.size = function () {
        return this.items.length
      }
      // 6.toString方法
      Stack.prototype.toString = function () {
        // 20 10 12 8 7
        let resultString = ''
        for (i = 0; i < this.items.length; i++) {
          resultString += this.items[i] + '--'
        }
        return resultString
      }

    }

    // 栈的使用
    var s = new Stack()
    s.push(20)
    s.push(10)
    s.push(100)
    s.push(44)
    s.push(24)
    console.log(s, 'push');
    s.pop()
    s.pop()
    alert(s, 'pop');
    alert(s.peek(), 'peek')
    alert(s.isEmpty(), 'isEmpty')
    alert(s.size(), 'size')
    alert(s.toString(),'toString')

  </script>
</body>

</html>